The Giant Radio Array for Neutrino Detection (GRAND) is a distributed, sparse ground antenna
array designed to detect the radio emission from highly inclined extensive air showers induced by
ultra-high-energy particles in the atmosphere. We use CoREAS air-shower simulations to adapt
an existing signal model of the radio emission of inclined showers to the 50 − 200 MHz frequency
band GRAND is sensitive to. The model uses a parameterisation of the charge excess emission to
isolate the geomagnetic component. By fitting a one-dimensional lateral distribution function to
the geomagnetic energy fluence of a shower, we reconstruct its radiation energy. This work details
the signal model and the intrinsic event reconstruction of our method, as well as the adaptations
to the new frequency band. This work is part of the NUTRIG project.